The seed pods of this vine look like green butterflies. I am in zone 9 and ie hardy here.

Seedpods are a winged chartreuse, papery and become tan as they ripen. They resemble butterflies....thus, the common name Butterfly Vine.

In addition to the bright yellow blooms, the seed pods add interest draw attention to this plant. (San Antonio, Tx.)

Notice the two colors of seed pods; the green pods turn brownish as they age ... (San Antonio, Tx.)

The seed is encapsulated in the "body" of the butterfly shaped seed pod shown here. I use both thumbnails to break apart the "body". Then, I roll the seed between my thumb and forefinger. If it crumbles, it is an old seed or insects have borrowed inside of it. If it does not crumble, it is viable. (San Antonio, Tx.)